“That” was Donald J. Trump’s inaugural news conference as a duly elected United States president-to-be, in which he called BuzzFeed a “failing pile of garbage,” dismissed CNN as “fake news” and more or less told the whole lot of reporters at Trump Tower to stuff it when it comes to his unreleased tax returns because everyday Americans don’t care and, anyway, “I won.”

There were two big lessons in the Wednesday morning melee.

1. Mr. Trump remains a master media manipulator who used his first news briefing since July to expertly delegitimize the news media and make it the story rather than the chaotic swirl of ethical questions that engulf his transition.

2. The news media remains an unwitting accomplice in its own diminishment as it fails to get a handle on how to cover this new and wholly unprecedented president.

It better figure things out, fast, because it has found itself at the edge of the cliff. And our still-functioning (fingers crossed) democracy needs it to stay on the right side of the drop.

Journalists should know this by now: Trump’s gonna Trump. But it’s time for them to take a page from the 12-step playbook — accept the things they cannot change and then find the courage to change the things they can, in the right ways, not the wrong ways.

Given Mr. Trump’s past behavior, there was hardly any doubt that he was going to kneecap his inquisitors on Wednesday. It’s a passion, after all, if not a strategic imperative.

But BuzzFeed handed him the steel rod hours before, with its decision to publish an unvarnished dossier filled with unsubstantiated, compromising reports about Mr. Trump allegedly collected by Russian agents, presumably for blackmail purposes.

BuzzFeed said it was “publishing the full document so that Americans can make up their own minds about allegations about the president-elect that have circulated at the highest levels of the U.S. government.” Ben Smith, the BuzzFeed editor in chief, wrote that “we have always erred on the side of publishing” and that “publishing this dossier reflects how we see the job of reporters in 2017.”

Mr. Smith’s stated rationale highlights the extent to which WikiLeaks and Gawker, which is now defunct, have changed the nature of journalism. Both have at times taken a “publish first, fill in the answers — or don’t — later” approach, but they held particular, outsider roles in the journalistic firmament. And both have run into great trouble because of their guns-blazing styles, in Gawker’s case, fatally (if wrongfully).

BuzzFeed, under Mr. Smith, has built up a fine traditional news team that has won journalism awards precisely because it succeeded in the ultimate purposes of its craft: to establish fact from fiction and enhance its readers’ understanding of reality. That’s the opposite of pumping out a bunch of unsubstantiated allegations and then leaving it to readers to “make up their own minds” about them with no reportorial guidance.

You can argue that the dossier was going to get out there anyway. But it hadn’t until BuzzFeed published it, even though many news organizations, including this one, had the dossier for months. And had they leaked by some other means, it would be up to journalists to establish their veracity; ignore them if possible, debunk them if necessary.

That’s what BuzzFeed has done with its top-notch reporting on the “fake news” phenomenon, helping to shine an early light on the false stories so many Americans were sharing on Facebook and other social media platforms throughout the campaign.

But every journalistic misstep gives more fodder to people who want to stop the efforts against “fake news” by turning the tables and labeling those efforts — or any other solid journalism they don’t like — as “fake news” as well, corrupting the term for their own purposes (a classic case of “no, you are!”).

That’s what Mr. Trump did Wednesday morning.

In calling BuzzFeed a “failing piece of garbage,” Mr. Trump gave it a cri de coeur. But there was collateral damage: Mr. Trump’s “fake news” charge against CNN, in front of many millions of Americans, went directly at the network’s core purpose as a global news provider.

CNN drew Mr. Trump’s hostility by breaking the news on Tuesday that a former British spy had compiled the Russia dossier and that intelligence officials included a synopsis of it in briefing materials for the president-elect. Once CNN opened the door, BuzzFeed followed by publishing the document itself.

But as CNN pointed out, it did not share the details of the memos, and it did not even link to the BuzzFeed report, despite false claims to the contrary by Kellyanne Conway, Mr. Trump’s adviser. Its decision, the network said, was “vastly different than BuzzFeed’s decision to publish unsubstantiated memos.”

That, in turn, drew protest from Mr. Smith of BuzzFeed, who said he was “not going to participate in an attempt to divide the media against each other.”

And so, Mr. Trump won again, by succeeding in doing just that. It was all part of a show in which he used news organizations as props in their own lampooning while he played them off each other with labels of good and bad and selectively answered their policy questions.

A united front would have given the reporters stronger footing. But that was woefully lacking when Mr. Trump shouted down Jim Acosta of CNN, who said Mr. Trump’s press secretary, Sean Spicer, threatened to eject him.

The other reporters in the room readily took Mr. Acosta’s place, happy to have their own questions answered. But they could be next. They’re going to have to decide how much they want to abide by Mr. Trump’s decision to selectively quarantine colleagues whose coverage he does not like.

There is some precedent for doing the right thing here, from the early days of the Obama administration, when it questioned Fox News’s credentials as a “news organization.” That was followed by an attempt by the Treasury Department to exclude Fox News from a round of interviews, which the rest of the news media resisted. Speaking in Fox News’s defense, Jake Tapper, then of ABC News, publicly criticized the administration for its effort to exclude “one of our sister organizations.”

So it was fitting that, later on Wednesday, Shepard Smith of Fox News got behind CNN. “It is our observation that its correspondents followed journalistic standards and that neither they nor any other journalists should be subjected to belittling and delegitimizing by the president-elect of the United States,” he said on his program.

(The same couldn’t be said for his colleague, the opinion host Sean Hannity — proudly “not a journalist” — who on Wednesday night celebrated the news briefing as “the single greatest beatdown of the alt-left abusively biased mainstream media in the history of the country.”)

Mr. Acosta, interestingly, made history last spring by becoming the first American journalist to ask a question of a Cuban leader, Raúl Castro, since the earliest days of the Castro regime. It was a hopeful sign of a new day for press freedom in the restrictive communist country.

His run-in with Mr. Trump, on the other hand, is a bad sign for press freedom at home. The news media can’t afford a backslide. It’s going to have to do its part to avoid one.